Perfume raw materials, selected from aldehydes, ketones, and mixtures thereof, are typically used to provide woody, floral, fruity or citrus notes to treatment compositions, and to substrates treated by such compositions. They are also highly preferred, since they provide an odour benefit at low concentrations. It is desirable to encapsulate such aldehydes and ketones into microcapsules, in order to provide long lasting, or in-use odour benefits.
Such microcapsules are typically made by cross-linking selected monomers together, in order to form a shell around a core material, which comprises the perfume raw materials to be encapsulated. Formaldehyde is a preferred monomer, in combination with another monomer which is capable of forming a cross-linked polymer network with formaldehyde. However, such microcapsules are known to slowly release free formaldehyde. In addition, residual amounts of formaldehyde typically remain after the microcapsules are formed. As a result, a formaldehyde scavenger is usually added to the treatment composition, to keep the formaldehyde level to within acceptable levels.
It has been found that treatment compositions containing such perfume microcapsules have poor colour stability. Moreover, the microcapsule slurries themselves often also exhibit poor colour stability. Therefore, a need remains for a treatment composition, particularly one that provides a long-lasting woody, floral, fruity or citrus character to the treated substrate, comprising microcapsules, while also having good colour stability.